GTSPP (Global Temperature and Salinity Profile Programme)

NetCDF Format Description

This section describes the netCDF conventions proposed by the NODC for use with the Global Temperature-Salinity Profile Program (GTSPP) data. The NetCDF conventions, also known as the GTSPP netCDF conventions, fully conform to the conventions used by the Cooperative Ocean/Atmosphere Research Data Service (COARDS) and World Ocean Circulation Experiment (WOCE). The COARDS/WOCE netCDF conventions have been widely recognized by numerous software plotting and analysis packages, for examples, ncBrowse and Ocean Data View, to provide more automatic processing, plotting, and analysis capabilities. It is very important that the GTSPP netCDF format files has the same capability as the WOCE data files have.

NetCDF Format Description

All GTSPP data is located by longitude, latitude, depth and time and is represented by three spatial axes (longitude, latitude, and depth) and one temporal (time) axis. Other information is not included as an axis, it must be included elsewhere within the data file, if the file is to be self-describing.

====
AXES
====
Axes
GTSPP data axis conventions are described here. Geographic axes in a GTSPP netCDF file are, at present, described by a numeric variable code included as an attribute in the data file. There is a disk file named "epic.key" which contains all EPIC variable codes with other related information. The numeric variable code is a unique identifier for the variable or axis, and is described more fully in the section below on "VARIABLES". The use of the numeric variable code to define the axis is necessary for EPS libary V2.1 and earlier, and for PPLUS V1.2c and earlier. In future releases of both the EPS libarary and PPLUS, the use of an axis variable code may be replaced by the use of units from UDUNITS, and may no longer be required.

Longitude axis
--------------

Many longitude representations are possible, however, for compatibility with the WOCE netCDF conventions, use East longitude convention, described in detail below, defines the numeric representation of the longitude axis in the netCDF file, with positive values for east longitudes. The recommended East longitude convention is described in the following paragraphs.

We recommend that users represent the longitude axis with the East longitude convention. This means that eastern longitudes are positive numbers, for example, 170E is +170.0. The units of the axis are degree_east.

Latitude axis
-------------
The recommended latitude convention is for north latitudes to be represented by positive numbers (e.g., 10N is +10.0), and south latitudes by negative numbers (e.g., 10S is -10.0). The units of the axis are degree_north.

Depth axis
----------
The depth axis should be given with the oceanographic convention of depth as a positive number, increasing downwards from the surface of the water towards the bottom of the ocean. The units of the axis should be dbar (pressure axis) or meters (depth axis).

Time axis
---------

The representation of the time axis within the data file can be of several types, including the WOCE standard, the double real numeric array, which will be "days since 1900-01-01 00:00:00 UTC", and some other time representations, which are supported for compatibility with the units used in the Argo netCDF convention - "days since 1950-01-01 00:00:00 UTC".

The standard units of the time axis EPIC system library routines return the time axis from a data file to the calling routine in the form of a two-integer array, in which the first integer is the "True Julian Day Number" with units of days, and the second integer is the number of milliseconds since 0000 GMT of the True Julian Day. The True Julian Day (eg, May 23, 1968 is 2,400,000), used by astronomers, should not be confused with the "year-day"
(eg, Feb 2 is year-day 33). The "year-day" is frequently called julian day (incorrectly) by oceanographers and meteorologists. Our double-dimensioned integer time word (word1=True Julian Day, word2=milliseconds since 0000 GMT of the True Julian Day) allows millisecond accuracy for time periods extending over centuries. There is a complete set of EPS routines for manipulation, calculation, and character string representation of this standard representation of time.

Time axes can be written or read in either real or integer format.

==========
VARIABLES
==========

Attribute Name	Attribute Value
Global Attribute Section
Conventions	CF-1.6
title	Global Temperature and Salinity Profile Programme (GTSPP) Data
summary	The data source is the GTSPP Continuously Managed Data Base
keywords	temperature, salinity, sea_water_temperature, sea_water_salinity
keywords_vocabulary	NODC Data Types, CF Standard Names
references	http://www.nodc.noaa.gov/gtspp/
institution	U.S. National Oceanographic Data Center
project	Joint IODE/JCOMM Global Temperature-Salinity Profile Programme
id	gtspp_dbid_13978451
naming_authority	gov.noaa.nodc
standard_name_vocabulary	CF-1.6
Metadata_Convention	Unidata Dataset Discovery v1.0
publisher_name	US DOC; NESDIS; NATIONAL OCEANOGRAPHIC DATA CENTER - IN295
publisher_url	http://www.nodc.noaa.gov/gtspp/
publisher_email	nodc.gtspp@noaa.gov
date_created	2012-05-01
date_modified	2012-05-01
date_issued	2012-05-01
history	2012-05-01T18:34:36Z writeGTSPPnc40.f90 Version 1.7
acknowledgment	These data were acquired from the US NOAA National Oceanographic Data Center (NODC) on [DATE] from http://www.nodc.noaa.gov/gtspp/.
license	These data are openly available to the public. Please acknowledge the use of these data with the text given in the acknowledgment attribute.
comment	GTSPP4.0 adapted the ACDD, COARDS, and CF-1.6 conventions including CF discrete sampling geometry for profiles.
featureType	profile
cdm_data_type	profile
geospatial_lat_min	30.43700
geospatial_lat_max	30.43700
geospatial_lon_min	-88.01200
geospatial_lon_max	-88.01200
geospatial_vertical_min	2.000000
geospatial_vertical_max	3.000000
geospatial_lat_units	degrees_north
geospatial_lat_resolution	point
geospatial_lon_units	degrees_east
geospatial_lon_resolution	point
geospatial_vertical_units	meters
geospatial_vertical_resolution	point
geospatial_vertical_positive	down
time_coverage_start	2012-04-27T10:30Z
time_coverage_end	2012-04-27T10:30Z
time_coverage_duration	point
time_coverage_resolution	point
gtspp_ConventionVersion	GTSPP4.0
gtspp_program	writeGTSPPnc40.f90
gtspp_programVersion	1.7
gtspp_handbook_version	GTSPP Data User's Manual 1.0
LEXICON	NODC_GTSPP

Variable ID Number	Variable Name	Variable Type	Number of Attributes	Number of Dimensions
Variable Metadata Section
1	format_version	char	2	1
2	gtspp_station_id	int	3	0
3	crc	char	3	1
4	best_quality_flag	int	4	0
5	time	double	5	1
6	time_quality_flag	int	5	0
7	latitude	float	5	1
8	longitude	float	5	1
9	position_quality_flag	int	5	0
10	qc_version	char	2	1
11	gtspp_temperature_instrument_code	char	5	1
12	gtspp_platform_code	char	2	1
13	data_type	char	3	1
14	one_deg_sq	int	1	0
15	cruise_id	char	5	1
16	source_id	char	3	1
17	stream_ident	char	3	1
18	uflag	char	3	1
19	no_prof	short	2	0
20	prof_type	char	1	2
21	z	float	13	1
22	z_variable_quality_flag	int	5	1
23	temperature	float	13	4
24	temperature_quality_flag	int	6	1
25	salinity	float	14	4
26	salinity_quality_flag	int	6	1
27	no_surf	short	1	0
28	surfacecodes_pcode	char	3	2
29	surfacecodes_cparm	char	2	2
30	no_hist	short	1	0
31	hist_identcode	char	1	2
32	hist_prccode	char	3	2
33	hist_version	char	2	2
34	hist_prcdate	char	2	2
35	hist_actcode	char	3	2
36	hist_actparm	char	3	2
37	hist_auxid	char	2	2
38	hist_ovalue	char	2	2
39	crs	int	6	0

Variable Name	Variable Type	Attribute Name	Attribute Value
Data Metadata Section
format_version	char
		long_name	File Format Version
		comment	Version number of the GTSPP NetCDF format
gtspp_station_id	int
		long_name	Station ID Number
		cf_role	profile_id
		comment	Identification number of the station in the GTSPP Continuously Managed Database
crc	char
		long_name	Cyclic Redundancy Check (CRC)
		_FillValue	X
		comment	A CRC algorithm used to generate an unique data tag of this record
best_quality_flag	int
		long_name	Best Quality Flag
		flag_values	0 1 2 3 4 5 6 7 8 9
		flag_meanings	no_quality_control_performed good_value probably_good probably_bad bad_value modified_value reserved reserved reserved missing_value
		references	http://www.nodc.noaa.gov/GTSPP/document/qcmans/qcflags.htm
time	double
		long_name	time
		standard_name	time
		units	days since 1900-01-01 00:00:00
		axis	T
		ancillary_variables	time_quality_flag
time_quality_flag	int
		long_name	Date-Time Quality Flag
		flag_values	0 1 2 3 4 5 6 7 8 9
		flag_meanings	no_quality_control_performed good_value probably_good probably_bad bad_value modified_value reserved reserved reserved missing_value
		_FillValue	-9
		references	http://www.nodc.noaa.gov/GTSPP/document/qcmans/qcflags.htm
latitude	float
		long_name	latitude
		standard_name	latitude
		units	degrees_north
		axis	Y
		ancillary_variables	position_quality_flag
longitude	float
		long_name	longitude
		standard_name	longitude
		units	degrees_east
		axis	X
		ancillary_variables	position_quality_flag
position_quality_flag	int
		long_name	Position Quality Flag
		flag_values	0 1 2 3 4 5 6 7 8 9
		flag_meanings	no_quality_control_performed good_value probably_good probably_bad bad_value modified_value reserved reserved reserved missing_value
		_FillValue	-9
		references	http://www.nodc.noaa.gov/GTSPP/document/qcmans/qcflags.htm
qc_version	char
		long_name	QC Program Version No.
		comment	Version of the QC program used.
gtspp_temperature_instrument_code	char
		long_name	GTSPP Temperature Instrument Code
		instrument_type	CTD
		recorder_type	Unknown
		comment	GTSPP code for temperature instrument type (first three digits, WMO-1770), with fall rate equation coefficients for XBT (last two digits, WMO-4770).
		references	http://www.nodc.noaa.gov/gtspp/document/codetbls/wmocode.html
gtspp_platform_code	char
		long_name	GTSPP Platform Code
		references	http://www.nodc.noaa.gov/gtspp/document/codetbls/calllist.html
data_type	char
		long_name	Data Type
		comment	TESAC message
		references	http://www.nodc.noaa.gov/gtspp/document/codetbls/gtsppcode.html#TYPE
one_deg_sq	int
		long_name	GTSPP geographic one degree square
cruise_id	char
		long_name	Cruise_ID
		callsign	MBLA1
		year	12
		_FillValue	X
		comment	Radio callsign + year for real time data
source_id	char
		long_name	Source ID
		_FillValue	X
		comment	Global Telecommunication System (GTS) node which placed message on the GTS
stream_ident	char
		long_name	Stream Identification
		_FillValue	X
		comment	Source and type of data. Bytes 1-2 show the data source center. Bytes 3-4 show data type
uflag	char
		long_name	Update Flag
		_FillValue	X
		comment	Record update action
no_prof	short
		long_name	Number of Profiles
		comment	Number of Parameter profiles in station
prof_type	char
		long_name	Profile Type
z	float
		long_name	Depths of the observations
		standard_name	depth
		units	meters
		deepest_depth	3.000000
		positive	down
		axis	Z
		ancillary_variables	z_variable_quality_flag
		data_min	2.000000
		data_max	3.000000
		C_format	%6.2f
		FORTRAN_format	F6.2
		epic_code	3
		_FillValue	99999.00
z_variable_quality_flag	int
		long_name	Depth/Press Quality Flag
		flag_values	0 1 2 3 4 5 6 7 8 9
		flag_meanings	no_quality_control_performed good_value probably_good probably_bad bad_value modified_value reserved reserved reserved missing_value
		_FillValue	-9
		references	http://www.nodc.noaa.gov/GTSPP/document/qcmans/qcflags.htm
temperature	float
		long_name	sea water temperature
		standard_name	sea_water_temperature
		units	degrees_C
		coordinates	time latitude longitude z
		grid_mapping	crs
		cell_methods	time:point lon:point lat:point z:point
		ancillary_variables	temperature_quality_flag
		data_min	19.80000
		data_max	19.80000
		C_format	%9.4f
		FORTRAN_format	F9.4
		epic_code	28
		_FillValue	99999.00
temperature_quality_flag	int
		long_name	Global quality flag of sea water temperature profile
		standard_name	sea_water_temperature status_flag
		flag_values	0 1 2 3 4 5 6 7 8 9
		flag_meanings	no_quality_control_performed good_value probably_good probably_bad bad_value modified_value reserved reserved reserved missing_value
		_FillValue	-9
		references	http://www.nodc.noaa.gov/GTSPP/document/qcmans/qcflags.htm
salinity	float
		long_name	Practical Salinity
		standard_name	sea_water_salinity
		salinity_scale	psu
		units	psu
		coordinates	time latitude longitude z
		grid_mapping	crs
		cell_methods	time:point lon:point lat:point z:point
		ancillary_variables	salinity_quality_flag
		data_min	2.900000
		data_max	2.900000
		C_format	%9.4f
		FORTRAN_format	F9.4
		epic_code	41
		_FillValue	99999.00
salinity_quality_flag	int
		long_name	Global quality flag of sea water salinity profile
		standard_name	sea_water_salinity_qc_flag
		flag_values	0 1 2 3 4 5 6 7 8 9
		flag_meanings	no_quality_control_performed good_value probably_good probably_bad bad_value modified_value reserved reserved reserved missing_value
		_FillValue	-9
		references	http://www.nodc.noaa.gov/GTSPP/document/qcmans/qcflags.htm
no_surf	short
		long_name	Number of Surface Codes Groups
surfacecodes_pcode	char
		long_name	Surface Parameter Code
		comment	Consult the GTSPP and WMO Code Tables to interpret what variable this is
		references	http://www.nodc.noaa.gov/GTSPP/document/codetbls/gtsppcode.html
surfacecodes_cparm	char
		long_name	Surface Parameter Value
		comment	Consult the GTSPP and WMO Code Tables to interpret what variable this is
no_hist	short
		long_name	Number of History groups
hist_identcode	char
		long_name	History Identification Code
hist_prccode	char
		long_name	History Processing Code
		references	http://www.nodc.noaa.gov/gtspp/document/codetbls/gtsppcode.html#PRC
		comment	Identifies the procedure through which the data passed.
hist_version	char
		long_name	History Processing Version
		comment	Identifies the version of the software through which the data passed.
hist_prcdate	char
		long_name	History Processing Date
		comment	Records the date as YYYYMMDD that this history record was created.
hist_actcode	char
		long_name	History Action Code
		references	http://www.nodc.noaa.gov/gtspp/document/codetbls/gtsppcode.html#PC_HIST
		comment	Identifies the action taken against the data by the software.
hist_actparm	char
		long_name	History Action Parm
		references	http://www.nodc.noaa.gov/gtspp/document/codetbls/gtsppcode.html#PC_PARM
		comment	Identifies the measured variable affected by the action.
hist_auxid	char
		long_name	History Auxilary Identification
		comment	Normally this is the depth at which the value of a variable was acted upon by the software.
hist_ovalue	char
		long_name	History Original Value
		comment	The original value before being acted upon by software.
crs	int
		long_name	Coordinate Reference System
		grid_mapping_name	latitude_longitude
		epsg_code	EPSG:4326
		longitude_of_prime_meridian	0.0f
		semi_major_axis	6378137.0
		inverse_flattening	298.257223563

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